Commit992446d

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GH-113462: Limit the number of versions that a single class can use. (GH-114900)

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+22

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Original file line number	Diff line number	Diff line change
`@@ -229,6 +229,7 @@ struct _typeobject {`
`229`	`229`
`230`	`230`	`/* bitset of which type-watchers care about this type */`
`231`	`231`	`unsignedchartp_watched;`
	`232`	`+uint16_ttp_versions_used;`
`232`	`233`	`};`
`233`	`234`
`234`	`235`	`/* This struct is used by the specializer`

Lines changed: 13 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -79,6 +79,19 @@ class C:`
`79`	`79`
`80`	`80`	`_clear_type_cache()`
`81`	`81`
	`82`	`+deftest_per_class_limit(self):`
	`83`	`+classC:`
	`84`	`+x=0`
	`85`	`+`
	`86`	`+type_assign_version(C)`
	`87`	`+orig_version=type_get_version(C)`
	`88`	`+foriinrange(1001):`
	`89`	`+C.x=i`
	`90`	`+type_assign_version(C)`
	`91`	`+`
	`92`	`+new_version=type_get_version(C)`
	`93`	`+self.assertEqual(new_version,0)`
	`94`	`+`
`82`	`95`
`83`	`96`	`@support.cpython_only`
`84`	`97`	`classTypeCacheWithSpecializationTests(unittest.TestCase):`

Lines changed: 2 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Limit the number of versions that a single class can use. Prevents a few`
	`2`	`+wayward classes using up all the version numbers.`

Lines changed: 6 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -908,6 +908,8 @@ type_mro_modified(PyTypeObject type, PyObject bases) {`
`908`	`908`	`}`
`909`	`909`	`}`
`910`	`910`
	`911`	`+#defineMAX_VERSIONS_PER_CLASS 1000`
	`912`	`+`
`911`	`913`	`staticint`
`912`	`914`	`assign_version_tag(PyInterpreterStateinterp,PyTypeObjecttype)`
`913`	`915`	`{`
`@@ -922,7 +924,10 @@ assign_version_tag(PyInterpreterState interp, PyTypeObject type)`
`922`	`924`	`if (!_PyType_HasFeature(type,Py_TPFLAGS_READY)) {`
`923`	`925`	`return0;`
`924`	`926`	`}`
`925`		`-`
	`927`	`+if (type->tp_versions_used >=MAX_VERSIONS_PER_CLASS) {`
	`928`	`+return0;`
	`929`	`+ }`
	`930`	`+type->tp_versions_used++;`
`926`	`931`	`if (type->tp_flags&Py_TPFLAGS_IMMUTABLETYPE) {`
`927`	`932`	`/* static types */`
`928`	`933`	`if (NEXT_GLOBAL_VERSION_TAG>_Py_MAX_GLOBAL_TYPE_VERSION_TAG) {`

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